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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

System Noise Prediction of the DGEN 380 Turbofan Engine

The DGEN 380 is a small, separate-flow, geared turbofan. Its manufacturer, Price Induction, is promoting it for a small twinjet application in the emerging personal light jet market. Smaller, and producing less thrust than other entries in the industry, Price Induction is seeking to apply the engine to a 4- to 5-place twinjet designed to compete in an area currently dominated by propeller-driven airplanes. NASA is considering purchasing a DGEN 380 turbofan to test new propulsion noise reduction technologies in a relevant engine environment. To explore this possibility, NASA and Price Induction have signed a Space Act Agreement and have agreed to cooperate on engine acoustic testing. Static acoustic measurements of the engine were made by NASA researchers during July, 2014 at the Glenn Research Center. In the event that a DGEN turbofan becomes a NASA noise technology research testbed, it is in the interest of NASA to develop procedures to evaluate engine system noise metrics. This report documents the procedures used to project the DGEN static noise measurements to flight conditions and the prediction of system noise of a notional airplane powered by twin DGEN engines.

Aircraft Design↗
NASA NTRS2015

System Noise Prediction of the DGEN 380 Turbofan Engine

The DGEN 380 is a small, separate-flow, geared turbofan. Its manufacturer, Price Induction, is promoting it for a small twinjet application in the emerging personal light jet market. Smaller, and producing less thrust than other entries in the industry, Price Induction is seeking to apply the engine to a 4- to 5-place twinjet designed to compete in an area currently dominated by propeller-driven airplanes. NASA is considering purchasing a DGEN 380 turbofan to test new propulsion noise reduction technologies in a relevant engine environment. To explore this possibility, NASA and Price Induction have signed a Space Act Agreement and have agreed to cooperate on engine acoustic testing. Static acoustic measurements of the engine were made by NASA researchers during July, 2014 at the Glenn Research Center. In the event that a DGEN turbofan becomes a NASA noise technology research testbed, it is in the interest of NASA to develop procedures to evaluate engine system noise metrics. This report documents the procedures used to project the DGEN static noise measurements to flight conditions and the prediction of system noise of a notional airplane powered by twin DGEN engines.

Aircraft Design↗
NASA NTRS2018

Acoustic Directivity of the DGEN Aero-propulsion Research Turbofan at Multiple Farfield Array Locations

The NASA Glenn Research Center's DGEN Aero-propulsion Research Turbofan (DART) is based on the Price Induction DGEN380 - a small, ~500-lbf thrust class, high-bypass, geared-turbofan engine with a separate flow nozzle. The general characteristics of the DART make it an ideal candidate for utilization as a test bed for engine aeroacoustic research in a relevant performance environment. To provide a baseline acoustic profile for the DART, the system was tested in the NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory. Acoustic measurements from multiple external arrays locations were acquired over the nominal fan operating range of 50-95%. The acoustic data are evaluated and reported in terms of overall, broadband, and tonal components. The existence of interaction tones (a result of the physics of the dual-spool interactions) are noted and presented. The symmetry of the acoustic directivity was measured in preparation for potential testing in other facilities.

Turbofan↗
NASA NTRS2018

Core/Combustor-Noise Baseline Measurements for the DGEN Aeropropulsion Research Turbofan

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. The new NASA DGEN Aeropropulsion Research Turbofan (DART) is a cost-efficient testbed for the study of core-noise physics and mitigation. This paper describes the recently completed DART core/combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). Acoustic data were simultaneously acquired using the AAPL overhead microphone array in the engine aft quadrant farfield, a single midfield microphone, and two semi-infinite-tube unsteady pressure sensors at the core-nozzle exit. Combustor-noise components of measured total-noise signatures were educed using a two-signal source-separation method and are found to occur in the expected frequency range. The acoustic data compare well with results from a limited 2014 feasibility test and will serve as a high-quality baseline for future research using the DART. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

Turbomachinery Noise↗
NASA NTRS2018

DGEN Aeropropulsion Research Turbofan (DART): Lossless Projection of Measured Engine Noise Spectra to a 1-Foot-Radius Arc

Baseline noise and aerodynamic data have been acquired for the DGEN Aeropropulsion Research Turbofan (DART) test rig. The DART is a fully-mobile engine test rig featuring a DGEN380 geared turbofan producing approximately 500 lbs. of thrust at sea level and a self-contained control room. Baseline noise data were acquired using 5 microphone arrays, varying distance, configuration, and angle to reflect the measurement locations at several other test facilities. Noise data were acquired at one array location on each test day to establish the repeatability of the measurements. The noise data from the different arrays is analyzed to show the limitations of projecting the results to a common radius when the noise sources are distributed and the measurement location is not in the geometric far-field.

Noise↗
NASA NTRS2018

Acoustic Directivity of the DGEN Aero-propulsion Research Turbofan at Multiple Farfield Array Locations

The NASA Glenn Research Center's DGEN Aero-propulsion Research Turbofan (DART) is based on the Price Induction DGEN380 a small, ~500-lbf thrust class, high-bypass, geared-turbofan engine with a separate flow nozzle. The general characteristics of the DART make it an ideal candidate for utilization as a test bed for engine aeroacoustic research in a relevant performance environment. To provide a baseline acoustic profile for the DART, the system was tested in the NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory. Acoustic measurements from multiple external arrays locations were acquired over the nominal fan operating range of 50-95%. The acoustic data are evaluated and reported in terms of overall, broadband, and tonal components. The existence of interaction tones (a result of the physics of the dual-spool interactions) are noted and presented. The symmetry of the acoustic directivity was measured in preparation for potential testing in other facilities.

Turbofan Engine↗
NASA NTRS2018

Core/Combustor-Noise Baseline Measurements for the DGEN Aeropropulsion Research Turbofan

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-eduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. The new NASA DGEN Aeropropulsion Research Turbofan (DART) is a cost-efficient testbed for the study of core-noise physics and mitigation. This paper describes the recently completed DART core/combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). Acoustic data was simultaneously acquired using the AAPL overhead microphone array in the engine aft quadrant far field, a single midfield microphone, and two semi-infinite-tube unsteady pressure sensors at the core-nozzle exit. Combustor-noise components of measured total-noise signatures were educed using a two-signal source-separation method and are found to occur in the expected frequency range. The acoustic data compares well with results from a limited 2014 feasibility test and will serve as a high-quality baseline for future research using the DART. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

Aeroacoustics↗
NASA NTRS2018

DGEN Aeropropulsion Research Turbofan (DART) Test Plans

This presentation serves as an overview of test plans for an upcoming DGEN Aeropropulsion Research Turbofan (DART) test entry at the NASA GRC AeroAcoustic Propulsion Laboratory (AAPL). The test entry includes: (1) a fan intra-stage velocity field survey, which will be compared to a Computational Fluid Dynamics (CFD) survey of DART, (2) an exploratory noise study of DART with several objectives focused on measurement projection to the far-field, source identification improvements and development of a barrier wall for isolation of various sources, (3) advancement of core/combustor noise research on DART using more extensive engine-mounted instrumentation, and (4) high-temperature pressure sensor technology-readiness-level (TRL) advancement.

Boyle, Devin K.↗
NASA NTRS2019

Acoustic Directivity and Insertion Loss Measurements of Advanced Liners Installed the Inlet of the DGEN Aeropropulsion Research Turbofan

The NASA Glenn Research Center’s DGEN Aeropropulsion Research Turbofan (DART) is based on the Price Induction DGEN380—a small, ~500-lbf thrust class, high-bypass, geared-turbofan engine with a separate flow nozzle. The general characteristics of the DART make it an ideal candidate for utilization as a test bed for engine aeroacoustic research in a relevant performance environment. The DART was used to document the efficacy of acoustic liners installed in the inlet of the DGEN380. An advanced multi-degree-of-freedom liner (MDOF) was designed and tested, along with a traditional single-degree-of- freedom liner (SDOF), and those results compared to a hard-wall baseline inlet. Farfield acoustic data were acquired from an external array, evaluated, and reported here-in terms of overall, broadband, and tonal components of the insertion loss.

Noise Reduction↗
NASA NTRS2019

One-Third-Octave Analysis of Core/Combustor-Noise Measurements for the DGEN Aeropropulsion Research Turbofan with Application to Noise Prediction

This work continues the analysis of data obtained during a 2017 NASA DGEN Aeropropulsion Research Turbofan (DART) core/combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). The DART is a cost-efficient testbed for the study of core-noise physics and mitigation. Acoustic data were simultaneously acquired using the AAPL overhead microphone array in the engine aft-quadrant farfield, a single midfield microphone, and two infinite-tube-probe sensors for unsteady pressures at the core-nozzle exit. The data are here examined on an 1/3-octave basis as a first step in extending and improving core-noise prediction capability.

Combustor Noise↗
NASA NTRS2019

Plans for Upcoming DGEN Aeropropulsion Research Turbofan (DART) Testing

This presentation serves as an overview of test plans for an upcoming DGEN Aeropropulsion Research Turbofan (DART) test entry at the NASA GRC AeroAcoustic Propulsion Laboratory (AAPL). The test entry includes: (1)a fan intra-stage velocity field survey, which will be compared to a Computational Fluid Dynamics (CFD) survey of DART, (2) an exploratory noise study of DART with several objectives focused on measurement projection to the far-field, source identification improvements and development of a barrier wall for isolation of various sources, (3) advancement of core/combustor noise research on DART using more extensive engine-mounted instrumentation, and (4) high-temperature pressure sensor technology-readiness-level (TRL) advancement.

Boyle, Devin K.↗
NASA NTRS2019

Design and Acoustic Efficacy of a Broadband Liner for the Inlet of the DGEN Aero-Propulsion Research Turbofan

Advanced fan designs (including higher bypass ratios) and shorter engine nacelles have highlighted a need for increased fan noise reduction over a broader frequency range. With these observations in mind, an acoustic liner optimization process has been developed to achieve improved broadband liner designs. A series of advanced liner design studies at increasing technology readiness levels have been conducted as the overall optimization methodology has been enhanced. As part of the analysis, the overall design and evaluation capability was extended such that external observer locations may be included in the optimization process. This enhancement will provide a much wider design space in designing advanced broadband liners. In this work, further validation was pursued through the fabrication and testing of two liner designs for the NASA Glenn DGEN Aero-propulsion Research Turbofan (DART). The DART was used to document the efficacy of acoustic liners installed in the inlet of the DGEN380. An advanced Multi-Degree of Freedom Liner was designed, fabricated, and tested, along with a traditional Single-Degree-of-Freedom Liner, and those results compared to a hardwall baseline inlet. Farfield acoustic data were acquired from and external array, evaluated and reported herein terms of overall, broadband, and tonal components of the insertion loss. The predicted attenuation results generally matched expected trends of the measured data for the conditions considered.

Liners↗
NASA NTRS2019

1/3-Octave Analysis of Core/Combustor-Noise Measurements for the DGEN Aeropropulsion Research Turbofan with Application to Noise Prediction

This work continues the analysis of data obtained during a 2017 NASA DGEN Aeropropulsion Research Turbofan (DART) core/combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). The DART is a cost-efficient testbed for the study of core-noise physics and mitigation. Acoustic data were simultaneously acquired using the AAPL overhead microphone array in the engine aft-quadrant farfield, a single midfield microphone, and two infinite-tube-probe sensors for unsteady pressures at the core-nozzle exit. The data are here examined on an 1/3-octave basis as a first step in extending and improving core-noise prediction capability.

Hultgren, Lennart S.↗
NASA NTRS2018

Broadband Inlet Liner Design for the DGEN Aero-Propulsion Research Turbofan

The utilization of advanced fan designs (including higher bypass ratios) and shorter engine nacelles has highlighted a need for increased fan noise reduction over a broad frequency range. With these observations in mind, an acoustic liner optimization process has been developed to achieve improved broadband liner designs. A series of advanced liner design studies at increasing technology readiness levels has been conducted as the overall optimization methodology has been enhanced. In this work, further validation was pursued through the fabrication and testing of two liner designs for the NASA Glenn DGEN Aero-propulsion Research Turbofan. Specifically, single and three layer liners were designed, fabricated, and tested. Analysis of the predicted attenuation results showed them to generally match expected trends for the conditions considered. The effects of source distribution on predicted directivity were also illustrated through the flexibility of a statistical source model. As part of the analysis, the overall design and evaluation capability was extended such that external observer locations may be included in the optimization process. This enhancement will provide a much wider design space for the development of advanced broadband liners. These preliminary results provide further confidence in the design tools and enhancements made to the overall liner design process.

Nark, Douglas M.↗
NASA NTRS2018

DGEN Aeropropulsion Research Turbofan (DART) Core/Combustor-Noise Infinite-Tube-Probe (ITP) Transfer Function

Direct measurements of turbofan engine core unsteady pressure is complicated by the extreme thermal environment within the engine, preventing currently available transducers from operating. It is necessary to use a remote measurement configuration such as an infinite-tube-probe (ITP) configuration in which the transducer is teed into a line pneumatically coupled with the location of interest and the other end of the ITP contains an "infinite" waveguide designed to prevent any reflections. This configuration has become a standard method for experiments concerning core noise. In order to relate the spectral pressure measurements obtained remotely with the ITP, a transfer (frequency response) function needs to be calculated based on a known pressure field. This is accomplished using a normal impedance tube at Glenn Research Center, where a flush-mounted microphone is used as a reference to the ITP signal in the calculation of the ITP's transfer function.

Boyle, Devin K.↗
NASA NTRS2020

DGEN Aeropropulsion Research Turbofan Source-Diagnostic Test: Experimental Setup and Acoustic-Data Structure

The experimental setup of, and available data from a recent core/combustor-noise source-diagnostic test utilizing a small turbofan engine are described. The 2019 test campaign continued the investigation of the core/combustor-noise component of aircraft-propulsor noise begun in an earlier baseline test, but with a more extensive acoustic-instrumentation layout. The purpose of both tests was to better understand the impact on civilian-transport airport-community noise from turbofan-combustor sources and thereby to lay the foundation for improved noise-prediction methods and noise-mitigation techniques. Simultaneous high-data-rate acoustic measurements were obtained using a circumferential sensor array at the core nozzle exit in conjunction with sideline and farfield microphone arrays. The test matrix contained engine operational points from engine idle to maximum power and was repeated for different circumferential and sideline array configurations, as well as for redundancy. The extensive data set (up to 93 channels of data and various configurations) allows the application of advanced source-separation and phased-array methods to elucidate not only the core-noise structure, but also the propagation characteristics of other propulsion noise sources. The present report provides a detailed description of the different test points, their associated instrumentation layouts, and the structure of the acquired data set. Results from various data analyses are reported separately.

Aeroacoustics↗